In recent years, along with the evolution of miniaturization technologies of 3C electronic products, portable products, such as mobile phone, tablet PC, smart glasses, wearable devices, etc., are gradually integrated into human daily life so as to make the human daily life more and more convenient. In addition, maintaining the electrical energy to operate the electronic product is the most critical subject. However, when the electronic products are used in a long time, the electricity is gradually consumed, so as to limit the range of application and convenience of the electronic products. Along with the rise of the mobile wearable devices, how to improve battery life and minimize the entirety of the mechanical design is the biggest problem that the portable electronic products will face in the future.
In the 3C electronic device systems currently available in the market, the energy harvesting techniques can be roughly divided into solar cell technology and wireless charging technology. The solar cell can use sunlight and ambient light to perform energy harvesting, however, in the environment without sunlight, the working efficiency of the solar cell is very low; the electromagnetic induction technology uses the characteristic that electromagnetic wave transforming to energy to perform energy harvesting, but inductive coupling is only used in a short distance to harvest energy; Although the millimeter-wave wireless charging technology may elongate the induction distance of the wireless charging, the harvest energy is lowest in three technologies.